Module: RuboCop::NodePattern::Macros

Included in:
Cop::Cop, Cop::Lint::NestedMethodDefinition, Cop::SafeAssignment, Cop::Style::ParallelAssignment::AssignmentSorter
Defined in:
lib/rubocop/node_pattern.rb

Overview

Helpers for defining methods based on a pattern string

Instance Method Summary collapse

Instance Method Details

#def_node_matcher(method_name, pattern_str) ⇒ Object

Define a method which applies a pattern to an AST node

The new method will return nil if the node does not match If the node matches, and a block is provided, the new method will yield to the block (passing any captures as block arguments). If the node matches, and no block is provided, the new method will return the captures, or ‘true` if there were none.



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# File 'lib/rubocop/node_pattern.rb', line 423

def def_node_matcher(method_name, pattern_str)
  compiler = RuboCop::NodePattern::Compiler.new(pattern_str, 'node')
  src = "def #{method_name}(node" \
        "#{compiler.emit_trailing_params});" \
        "#{compiler.emit_method_code};end"

  file, lineno = *caller.first.split(':')
  class_eval(src, file, lineno.to_i)
end

#def_node_search(method_name, pattern_str) ⇒ Object

Define a method which recurses over the descendants of an AST node, checking whether any of them match the provided pattern

If the method name ends with ‘?’, the new method will return ‘true` as soon as it finds a descendant which matches. Otherwise, it will yield all descendants which match.



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# File 'lib/rubocop/node_pattern.rb', line 439

def def_node_search(method_name, pattern_str)
  compiler = RuboCop::NodePattern::Compiler.new(pattern_str, 'node')
  if method_name.to_s.end_with?('?')
    on_match = 'return true'
    prelude = ''
  else
    yieldval = compiler.emit_capture_list
    yieldval = 'node' if yieldval.empty?
    on_match = "yield(#{yieldval})"
    prelude = "return enum_for(:#{method_name}, node0" \
    "#{compiler.emit_trailing_params}) unless block_given?"
  end

  src = node_search_body(method_name, compiler.emit_trailing_params,
                         prelude, compiler.match_code, on_match)
  filename, lineno = *caller.first.split(':')
  class_eval(src, filename, lineno.to_i)
end

#node_search_body(method_name, trailing_params, prelude, match_code, on_match) ⇒ Object 



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# File 'lib/rubocop/node_pattern.rb', line 458

def node_search_body(method_name, trailing_params, prelude, match_code,
                     on_match)
  <<-END
    def #{method_name}(node0#{trailing_params})
      #{prelude}
      node0.each_node do |node|
        if #{match_code}
          #{on_match}
        end
      end
      nil
    end
  END
end